Method and apparatus for implementing process-based security in a computer system

ABSTRACT

A method is disclosed for providing process-based security in a special purpose computer system, comprising the steps of: configuring the special purpose computer with an operating system and at least one application for operation as a computer appliance; associating a resource access table with the at least one application, addressable by the at least one application, containing statements corresponding to predetermined requests for access to at least a one specified resource during running of the at least one application wherein the resource access table statements include information defining an execution path for the at least one application; interpreting the resource access table statements upon a request for the specified resource by the at least one application, wherein at least one of the statements in the resource access table provides for performing a security check prior to granting access to the specified resource; and causing the execution of the at least one application, upon granting access to the requested resource, including the use of the requested resource according to the execution path statements in the resource access table.

TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates in general to software securitysystems and, more particularly, to a process-based system forcontrolling access to resources in a computer system.

BACKGROUND OF THE INVENTION

[0002] Data processing systems have, as of recent, seen a large increasein the use thereof. For small users, such as home users, a typicalsystem will run multiple programs that will allow access to variousstored data files, allow the user to access resources such as diskdrives, modems, faxes, etc. Access to these types of systems istypically what is referred to as “unrestricted”, i.e., any onepossessing the required knowledge to access a given program can accessit on any unrestricted computer. However, for a larger data processingsystem that may contain confidential information, the user may beprovided access to resources that are billed on a time-use, etc., thesesystems usually requiring restricted access.

[0003] In restricted access systems, a user is typically given an I.D.to the system. A system administrator can then configure a system, via anetwork or even a stand-alone system, to define the user's access to thesystem, once the user has logged in to the system. For example, in thenetwork environment, there are a plurality of network drives, networkresources such as printers, faxes and mailboxes, etc. The user has aconfiguration file that defines what access the user has. Upon loggingin, the network will then access the configuration table and allow thatuser access to the given system resources. The user can then execute aprogram and utilize the program to access the resources throughsomething as simple as a disk operating system (DOS). The disadvantageto this type of access is that the user now has full access to resourcesfor any purpose, other than the purpose for which the user was givenaccess.

[0004] As an example, a user may need access to a modem for the purposeof running database searching software. This database searching softwareallows the user to dial up a provider with the modem to performpredefined searching. In order for a prior restricted system to utilizethe modem, the user must be granted access to a given serial port.However, the user need not run the database searching software in orderto have access to the modem. This allows the user to run other programsthat can gain access to the system. The disadvantages to this is that,although the database searching software may have certain restrictionsthat are inherent in the software itself, a user can bypass this systemto utilize the modem for other purposes. This can also be the case withrespect to data files, wherein a word processing program has the abilityto read and write files and gain access to printers through the wordprocessing software. However, this access must be granted in a globalmanner, such that the user can access the files and printers via anyother means, once logged into the system.

[0005] As another example, consider a database that allows access todatabases such as payroll, criminal records, etc., which a user has beengiven access. With current operating system security, the user cancertainly go outside of a given program that is utilized with a specificdatabase to copy, delete or even change files in the database outside ofthe program. As such, there exists a problem in that security forcurrent operating systems provides that resources are allocated based onusers or the groups to which the users belong. This therefore allows theuser access to those resources even though the process that needs thoseresources is not being run. These rights will in turn allow the user touse the resource outside of its intended use.

[0006] In a general purpose computer system operating with a wideassortment of applications or processes, usually as part of a bundledpackage, security is based on the control of user access which allowsaccess to all of the resources on the system whether they are needed ornot. A disadvantage of this system is that it is not very secure and isprone to break-in or misuse of resources, some of which contain verysensitive information, primarily because of the unrestricted access toresources. All that is required to enter such a system is a user ID anda password. One solution, implementing process-based access to a generalpurpose computer system, where the access to each resource is controlledin addition to the entry of a user ID and password, would provide anadditional level of access control. However, in a general purpose systemrunning many applications with numerous resources, such a solution wouldbe very cumbersome to implement and use as well as very inefficient inthe use of system resources.

SUMMARY OF THE INVENTION

[0007] A dedicated, single purpose computer system is disclosed whichtypically operates with a predetermined set of a relatively small numberof applications or processes and requires correspondingly fewerresources. In such a dedicated or single purpose system, a web server ora computer appliance-type machine, for example, lends itself readily toprocess-based security. In addition to the entry of a user ID and apassword, the access to each of the resources needed by each applicationmay be individually controlled with only minimal burden upon systemresources. The present invention disclosed and claimed herein, in oneaspect thereof, comprises a method for providing process-based securityin a dedicated computer system configured with an operating system andat least one application program. The method comprises the steps ofconfiguring the special purpose computer with an operating system and atleast one application for operation as a computer appliance, associatinga resource access table with the at least one application, addressableby the at least one application, containing statements corresponding topredetermined requests for access to a specified resource during runningof an application wherein the resource access table statements includeinformation defining an execution path for the application; interpretingthe resource access table statements upon a request for the specifiedresource by the application, wherein at least one of the statements inthe resource access table provides for performing a security check priorto granting access to the specified resource; and causing the executionof the application, upon granting access to the requested resource,including the use of the requested resource according to the executionpath statements in the resource access table.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] For a more complete understanding of the present invention andthe advantages thereof, reference is now made to the followingdescription taken in conjunction with the accompanying Drawings inwhich:

[0009]FIG. 1 illustrates a block diagram of an overall system;

[0010]FIG. 2 illustrates a prior art security system;

[0011]FIG. 3 illustrates a general block diagram of the system of thepresent invention;

[0012]FIG. 4 illustrates a more detailed block diagram of the system ofthe present invention;

[0013]FIG. 5 illustrates an alternate embodiment of the system of thepresent invention;

[0014]FIG. 6 illustrates a flowchart depicting the operation of thepresent invention;

[0015]FIG. 7 illustrates a flowchart depicting the resource request bythe process;

[0016]FIG. 8 illustrates a flowchart depicting the processing of therequest by the operating system;

[0017]FIG. 9 illustrates a functional block diagram of an embodiment ofa process-based security system according to the present disclosure;

[0018]FIG. 10 illustrates a flowchart of the operation of the embodimentof the process-based security system of FIG. 9; and

[0019]FIG. 11 illustrates a flowchart of an example of use of a resourceaccess table according to the embodiment of FIG. 9.

DETAILED DESCRIPTION OF THE INVENTION

[0020] Referring now to FIG. 1, there is illustrated an overall blockdiagram of a system for operating in conjunction with the securitysystem of the present invention. A central processing unit (CPU) 10 isprovided, which CPU 10 has associated therewith a microprocessor,peripheral circuitry, power supply, etc., all required to executeinstructions and, in general, run programs. The CPU 10 has associatedexternal therewith a keyboard 12 to allow the user to input theinformation thereto and a display 14. A disk input system 16 is alsoprovided which allows the user to download and upload data. The CPU 10also has a local memory 18 associated therewith, the local memory 18being in the form of random access memory, read-only memory, andmagnetic storage media such as a disk drive. The local memory 18 isoperable to store both files in a region 20 and also execute programs ina region 22. The files in the region 20 can also consist of data fordatabases. The CPU 10 can then access the executable files in theprogram portion 22, execute the programs and access information in theform of files and/or data.

[0021] The CPU 10 also interfaces with peripheral resources through anInput/Output (I/O) block 24. The I/O block 24 allows access to suchthings as a modem 26, a network card 28, a scanner 30 and a printer 32.The scanner 30 and the printer 32 are referred to as local resources.The modem/fax 26, however, allows access to remote resources, such as apublic telephone network (PTN) 34. The network card 28 allows access toa network 36, which in turn allows access to network resources 38.

[0022] Referring now to FIG. 2, there is illustrated a block diagram ofa prior art security system. In prior art security systems, a userrepresented by a block 40 is allowed to access the system only uponproviding the correct user I.D. A system administrator 42 is operable topre-store configurations for the users in a user resource accesstemplate 44. This user resource access template is accessed whenever auser is brought into the system and attempts to log in to the system.Once the user logs in, each user is given a predetermined configuration,this referred to as user access blocks 46, there being one associatedwith each user. Each of these user access blocks 46 contain theconfiguration that was pre-stored by the system administrator 42 in theuser resource access template. Once configured, this defines how theuser is interfaced with the system, the system comprised of a pluralityof system resources, represented by blocks 48. In the exampleillustrated in FIG. 2, there are provided five system resource blocks48.

[0023] It can be seen in the prior art system of FIG. 2 that there arethree user access blocks 46, representing three different userconfigurations, although there could be more, and five separate systemresources, although there could also be more of these. The user accessblock associated with the user No. 1 is associated with system resource1 and system resource 2. User access block 46 associated with user No. 2has access to system resource No. 1, system resource No. 3 and systemresource No. 4. Associated user access block 46 provides a configurationthat allows user No. 3 access to system resource 1 through 5. It isnoted that this is independent of the process upon which the user isworking. The system resource is accessible by the user and not by theprocess.

[0024] Referring now to FIG. 3, there is illustrated an overall blockdiagram of the present invention. In the present invention, security isbased upon a process. A process, such as a word processing program, afinancial program, etc., each have certain needs related to theresources. For example, a payroll program, once accessed, would need tohave access to its database. The program, however, typically does notallow as an inherent part thereof for the database to be copied, doesnot allow the database to be deleted nor manipulated in any manner otherthan that provided by the program itself. These may even have audittrails that cannot be bypassed. The present invention provides forsecurity wherein the resource is only accessible through the step ofexecuting and running the program. If the program is not running, theuser does not have access to the given resource unless through anotherprocess which happens to have access to the resource.

[0025] Referring further to FIG. 3, a general operating system 60 isillustrated, this operating system being any type of operating systemsuch as a Microsoft Windows based system, a UNIX system or even a DOSsystem. An operating system is the primary method by which a computerinterfaces between the peripheral systems, such as memory storagedevices, printers, modems and a process running on said computer. Theuser is then provided with a platform on which to run programs whereinthe user can access the program and have the program access variousperipherals through its interaction with the operating system. Operatingsystem 60 therefore provides the necessary commands to access variousresources 62 on the system. Again, these resources can be such things asa modem, a printer, a scanner, etc., even including a magnetic diskdrive. The operating system is restricted to allocate only thoseresources defined in a resource access table 64, which resource accesstable defines resources associated with a given process, whichassociation is based upon the process' needs.

[0026] The process expresses its need via a process requesting mechanism66 which is an inherent aspect of process execution for any givenprocess. The process requesting mechanism 66 initiates a request for aresource and, if the process running on the system has access to thatresource, as noted in the resource access table 64, the operating system60 will then grant the resource for use by the process within theoperating system. If not, then the operating system will block access.

[0027] Referring now to FIG. 4, there is illustrated a more detailedblock diagram of the process-based access system of the presentinvention. In general, a user block 68 is provided which indicates auser of the system. The user of the system can access any given process,being illustrated for processes in process blocks 70. Each of theprocess blocks 70 is connected to a process access selector 74, each ofwhich is associated with one of the resource blocks 62, there beingillustrated five resource blocks 62. The process access selector 74 isoperable to potentially allow any process to address that process accessselector 74. An access control block 76 is provided that receives asinputs an indication of which of the processes in process block 70 isrunning. A System Administrator block 75 is provided to allow a SystemAdministrator to set the parameters of the access control block. Theaccess control block then selects which of the process access selectorblocks 74 is authorized to have access to a given resource. It isimportant to note that it is a request from a process block 70 duringthe running of that process that is utilized by the access control block76 to grant access to the process access selector 74.

[0028] By way of example, if a word processing program were beingoperated and, on the same computer, a user had the ability to operate anaccounting program, the word processor would be provided access tocertain regions on a disk and the files associated therewith. The usercould retrieve these files, delete them, modify them and restore them.However, the user would not be allowed through the word processor toaccess the accounting database for any purpose, since the process doesnot require this. In another example, if a modem were provided, thiswould not usually be a resource that was available to a word processor.The modem would, for example, only be accessible to a communicationsprogram.

[0029] In another example of the operation of the process based securitysystem, where resources are permitted access only in association withthe particular process that is selected, reference is made to Table 1,which is an example of the resource access table 64 of FIG. 3: TABLE 1Step Process name Resource name Rights Mask 1 C:\*.*/S C:\*.*/S Fullaccess E:\LOGIN\LOGIN.EXE Execute only 2 E.\LOGIN\LOGIN.EXEE:\SYSTEM\PASSWORDS Read only E:\PROGRAMS\MENU\MENU.EXE Execute only 3E;\PROGRAMS\MENU\MENU.EXE E:\PROGRAMS\MENU\SCREENS Read onlyE.\PROGRAMS\*.EXE/S Execute only E:\PROGRAMS\*.COM/S Execute only 4E:\PROGRAMS\WP51\WP.EXE F.\LIBRARY\*.* Full access G:\COMMON\*.*/S Fullaccess

[0030] The example in Table 1 illustrates a general personal computer ofthe clone type, running an MS DOS operating system which is attached toa network with a process based security. When the computer is started,any process with the C:\ drive (denoted with the wild card processing of*.*) and its sub-directories (denoted with the \S option on the end ofthe process name) is provided full access to anything on the C:\ drive(once again denoted with the wild card resource name of *.*) and itssub-directories (once again denoted with the \S option on the end of theresource name). The user can also execute the process E:\LOGIN\LOGIN.EXEfrom the network. All other resources from the network are not availableto the computer at this time. This situation represents a user, on acomputer, who can log into a network, but has not done so. In essence,the user can do anything with their local resources, but nothing withnetwork resources, until they are identified to the network with thelogin program.

[0031] In step 2 in Table 1, when the user executes theE:\LOGIN\LOGIN.EXE process, the process changes from something on C:\ toLOGIN.EXE which can read the E:\SYSTEM\PASSWORDS file and execute theE:\PROGRAMS\MENU\MENU.EXE program. The file LOGIN.EXE is the network'smethod of identifying users of the network. Execution of LOGIN.EXE willverify the user through its read-only access to the E:\SYSTEM\PASSWORDSfile. If the user is verified as a valid user, LOGIN.EXE will passcontrol on to step 3 and the process E:\PROGRAMS\MENU\MENU.EXE.

[0032] In step 3, when MENU.EXE gets executed, it will read theappropriate menu options from its SCREENS file and display it for theuser. MENU.EXE controls what programs can be executed and as such, ithas been given rights to execute any program in the E:\PROGRAMSdirectory or any of E:\PROGRAMS sub-directories (this is denoted withthe /S option after the partial wild card name *.EXE and *.COM). In step4, in the event the user executes the WP.EXE program, this process hasfull access to a local F:\LIBRARY directory, a shared G:\COMMONdirectory and the sub-directories of G:\COMMON. The example in step 4may also represent a network, where personal files are stored in auser-related directory (F:\LIBRARY) and company shared documents arestored in a common directory (G:\COMMON).

[0033] In the preceding example, it can be seen that the user cannot,for example, obtain access to the PASSWORDS file by any other processexcept for the LOGIN.EXE process and this process determines how theuser can deal with that particular file.

[0034] Referring now to FIG. 5, there is illustrated an alternateembodiment of FIG. 4, illustrating how a particular process canconstitute a resource. The resource blocks include a resource block 80which constitutes a sixth resource, in addition to the five resourceblocks 62. However, this resource also has a process block 82 disposedtherein, which constitutes a fifth process. Access to this process block82 is facilitated through the use of a process access block 84, similarto the process access block 74, and controlled by access control 76.Each of the processes in process blocks 70 have access to the processblock 82 and the resource block 80 through the process access block 84.Therefore, if one of the processes in process blocks 70 were running andthe access control block 76 allowed access through a process accessblock 84, then process No. 5 in resource block 80 could be run. This, ofcourse, would then allow process block 82 and the process #5 associatedtherewith to request and receive access to any of the resources inresource blocks 62 associated with process access block 74 in accordancewith the access control information in access control block 76. Althoughillustrated as only a single process that is accessed by anotherprocess, there could be many processes deep, such that three or fourprocesses would need to be run before a given process was accessiblewhich, in turn, could access an end resource.

[0035] It is important to note that the process must be running and,during the running thereof, execute instructions that request a givenresource. It is the running of the process and the request by thatrunning process that allows access to a resource. The fact that theprocess has been opened and initiated is not sufficient to gain accessto the resource since it is the use of the resource by a given processthat is selected. For example, if a multi-tasking operating system wereutilized and a given program executed from that platform as a firsttask, it may be desirable to place that task in the background andinitiate a second task. Even if the first task were running in thebackground, the ability of the first task to request a given resourcedoes not in any way effect the rights of the second task to have accessto that same resource. Unless it is in the resource access table, noaccess to the resource will be allowed. Even if the first task wereoperating and it were utilized to “launch” a second process, this wouldnot effect the resource access of the launched process, since when thelaunched process is running, the launching process is not running and itis not the launching process that is requesting access to the resource.Therefore, it is only the requesting resource that is of concern.

[0036] Referring now to FIG. 6, there is illustrated a flowchartdepicting the overall operation of the system. The program is initiatedat a start block 100 and proceeds to a decision block 102. The decisionblock 102 determines if a process has been initiated. If not, theprogram flows back around an “N” path to the input of decision block102. When a process has been initiated, the program will flow to afunction block 104 to log in the user. The log in procedure is aprocedure that may be utilized, but can be optional. In and of itself,as described above with reference to Table 1, the log in process is aseparate process in and of itself. However, some programs by themselves,require log in procedures, i.e., accounting systems. Therefore, this isan optional block.

[0037] After the log in block 104, the program will flow to a functionblock 106 to run the process. Once the process is running, the programthen flows to a decision block 108 to determine if a resource requesthas been made by the running process. If not, the program will flowalong the “N” path back to the input of function block 106. When aresource request has been made by the running process, the program willflow from decision block 108 along a “Y” path to a function block 110,wherein the resource access table is accessed to determine access rightsfor the requesting process. The program will then flow to a decisionblock 112 to determine if access has been granted for that particularresource. If not, the program will flow along a “N” path to a functionblock 114 to return an “access denied” error code. The program will thenflow back to the input of function block 106. However, if access rightshave been granted in accordance with the resource access table, theprogram will flow along a “Y” path from decision block 112 to a functionblock 116 to allow access to the system and then back to the input offunction block 106. This will continue unless the resource is halted.

[0038] Referring now to FIG. 7, there is illustrated a flowchartdepicting the resource request by the process, as in step 108 of FIG. 6.The flowchart is initiated at a block 120 and then proceeds to adecision block 122, wherein the process determines if a resource isneeded for the process. If not, the program flows along an “N” path backto the input of decision block 122. If a resource is required, theprogram will flow along a “Y” path to a function block 124. The functionblock 124 then determines the ID for the resource and then generates therequest, this request defining the resource that is required and alsothe mode of access that is required. The program will then flow to adecision block 126 to determine if the resource is available. If not,the program will flow along an “N” path back to the input of decisionblock 122. If it is available, the program will flow along a “Y” path toa function block 128 to process the resource in accordance with theoperation of the process and then flow to a return block 130.

[0039] Referring now to FIG. 8, there is illustrated a flowchartdepicting the operation of the operating system when processing arequest for a resource. This is initiated at a block 134 and thenproceeds to a decision block 136. The decision block 136 determineswhether a resource request has been received from a process operating inconjunction with the operating system. If not, the program will flowalong an “N” path back to the input of decision block 136. If a resourcerequest has been received, the program will flow along the “Y” path to afunction block 138. Function block 138 fetches the information stored inthe resource access table to determine if the particular resource hasany access rights associated therewith. The program will then flow to adecision block 140 to determine if access rights are present in theresource access table for the requested resource. If not, the programwill flow along the “N” path to a function block 142 wherein a “NULL”signal is sent back to the requesting process to deny access and then tothe input to decision block 136.

[0040] If access rights exist in the resource access table for the givenresource, the program will then flow to function block 144 to determineif the mode of access that is requested by the requesting process ispresent in the resource access table, i.e., whether the resource accesstable has been set up to grant this mode of access to the givenresource. An example of this would be a file that is defined as theresource with the modes being READ and WRITE, with either reading of thefile from the disk or writing of the file to disk. The program will thenflow to a decision block 146 to determine if the mode of access isavailable. If not, the program will flow along the “N” path back to thefunction block 142 and, if the mode of access is available, the programwill flow along the “Y” path to a decision block 148 to determine if therequested resource and mode of access are valid for the requestingprocess. For example, a process may request access to a particularmemory device or portion of a memory device and it may require access tothat memory device for writing of information thereto. The system willfirst determine if the resource has access rights associated therewithand then check to see what mode of access is allowed. In this example,if the resource is available, it may have a mode of access available forreading and a mode of access available for writing. However, theresource access table may only grant reading rights to the requestingprocess. In this event, access will be denied. This is represented bythe path that flows along the “N” path back to function block 142. Ifaccess is allowed, the program will flow along a “Y” path from decisionblock 148 to a function block 150 to grant access and then to a returnblock 152. The following is the process flow for the process generatingthe request: id = fopen (“filename”, “rt”); ← This is the request to theoperating system for the file access (resource). if (id == NULL) { filenot available } else { process the opened file }

[0041] The following is the process flow for the operating system whenservicing the request:

[0042] Operating System FILE *fopen (char *name, char *mode) { (beforechecking for the presence of the file, check to see if the process hasany rights to the file.) for (i = øi<SIZE_OF_ACCESS_TABLE; i++) if(check (name, accesstable [i]. resource) == ø) break; if (i ==SIZE_OF_ACCESS_TABLE) return NULL; (no rights at all) for (j = ø;j<accesstable [i]. rights_size; j++) if (check (mode, accesstable [i].rights[j]. Mode) == ø) break; if (j == accesstable [i] rights size)return NULL; (specific right not present) (the remaining code deals withwhat the operating system needs to do to allocate the file to thecalling process (note additional errors may still occur, like file notfound)). }

[0043] The foregoing describes a system for providing process-basedsecurity to an operating system. In this security system, access to anyresource on the system, although provided by the operating system, isrestricted by the operating system to only those requested by a givenprocess. Whenever a process, during operation thereof with the operatingsystem, requires or requests access to a resource, the operating systemmakes a determination as to whether a resource can be made available forthat given process. This is facilitated by storing access rights for anyprocess in a resource access table. When a process is running on thesystem and it requests for its use a given resource, the operatingsystem will then look up in the resource access table to determine ifthe resource is available and, if so, grant access to the resource.

[0044] It has been described hereinabove that a process-based securitysystem controls access to resources via the process (i.e., application)that requests the resource. Experimentation and development have shown,however, that such a security system is more efficiently implemented ina dedicated, or single-purpose environment, such as a web server, orother, computer appliance-type of application. In a general purposesystem, where user-based access is the standard and allows the useraccess to all resources, it may not be as easy to justify limitingaccess based on process because so many processes may be available,making the process-based access more complex, or less efficient andperhaps redundant due to the complexity and global scope that might berequired for implementation in a general purpose system.

[0045] Thus, it can be appreciated that the process-based securitydescribed hereinbelow, as applied to a dedicated, single purposecomputer system, could exhibit the following advantages:

[0046] (1) prevent a user from loading their own applications into thesystem;

[0047] (2) prevent a user from attempting to access files fromuncontrolled processes, e.g., trying to load in a hex editor to obtainaccess to the sensitive files such as accounting records, etc.;

[0048] (3) prevent access to all the resources in a system, even thoughindividual resources are needed by a particular program or process;

[0049] (4) process-based security, in a dedicated environment, is selfcontained, i.e., independent of the rest of the system, and is thusrelatively easy to implement in existing systems;

[0050] (5) process-based security is context-specific and can be made tobe dynamic by the way in which resource access is interpreted; and

[0051] (6) in a process-based security system, the user only has theright to execute a specific application or process and that processincludes access rights only to specific resources keyed to therequesting process.

[0052] Referring to FIG. 9 there is illustrated a functional blockdiagram of an illustrative embodiment of a process-based security systemaccording to the present disclosure. A portion of the functional aspectsof a complete computer system 160 is shown having an operating system162 coupled with a plurality of resources indicated by the three blocksidentified by reference number 172, respectively resource A, resource Band resource C. In general, resources 172 may be various types of inputand/or output devices or application programs installed on a particularsystem. I/O device resources may include a keyboard, mouse, scanner,display, modem, disk drive, printer, or an interface to a network, etc.Application, or process type resources may further include a wordprocessor, a spreadsheet, a communication or e-mail program, a database,a search engine or browser and the like. Continuing with FIG. 9, eachprocess requesting access 168 is bound to a resource access table (RAT)164 via respective links 165, 166 and 167. The resource access tables164 contain entries or statements that may be expressed in a high levelprogramming language. Further coupled as inputs to operating system 162are the plurality of processes requesting access 168, i.e., applicationsrunning on system 160 as indicated by process requesting access 1,process requesting access 2 and so on to process requesting access N. Inthe description to follow, the words application and process will beused interchangeably, referring generally to an application program asdistinguished from an operating system. Such application programs areprovided to accomplish specific operations such as spread sheets or wordprocessing or communications and the like. In general, each of theseprocesses or applications 168 will, during their operation, requireaccess and use of various ones of the resources 172 coupled to theoperating system 162 of the computer system 160 of the presentdisclosure. Coupled as inputs to the various processes 168 orapplications 168 is provision for entering a user identifier and/orpassword for each respective process 168 or application 168 that will berequesting access to a resource as will be described furtherhereinbelow. The entry of the user identifier and/or password isrepresented by the functional block 170 user ID and password.

[0053] Referring further to FIG. 9, an operating system 162 for computersystem 160 is illustrated, such as a Microsoft Windows based system, aUNIX system, a DOS system or the like. An operating system is theprimary method by which a computer interfaces with the various resourcesincluding, for example, the peripheral systems such as memory storagedevices, printers, modems and a process or application running on saidcomputer. The operating system 162 provides the user with a platform onwhich to run programs, i.e., applications or processes 168 wherein theuser can access the program and have the program access variousperipherals through its interaction with the operating system. Operatingsystem 162 therefore provides the necessary commands to access variousresources 172 on the system. Further, the operating system 162 isrestricted to allocate only those resources defined in the resourceaccess tables 164, which define resources 172 to be associated with agiven process 168, based upon the needs of the process 168.

[0054] The operating system 162 (OS 162) receives as inputs anindication of which of the process blocks 168 is running. In oneembodiment the OS 162 may include or be responsive to a SystemAdministrator function to set the parameters of the access control forthe resources 172. The OS 162 in conjunction with the resource accesstable 164 then selects which of the resources 172 is authorized access.It is important to note that it is a request from a process 168 duringthe running of that process 168 that is utilized by the OS 162 to grantaccess to the resource access table 164.

[0055] Continuing with FIG. 9, the functional block 170 indicates both auser of the system and information that may be provided by the user togain access to the system or its resources. The user of the system canaccess any given resource appropriate to the application that isprovided in the dedicated system. In general, a process or anapplication is an executable file which may be referred to as “*.EXE”,the “*” defining a wild card name of one or more characters representingan executable file or program. For example, one well known wordprocessing program has an executable file name of WP.EXE. The user canenter the term “WP” and “launch” that program. The program will then runin a conventional manner.

[0056] In operation of the system 160 of FIG. 9, by way of example, if aword processing program were being operated and, on the same computer, auser had the ability to operate an accounting program, the wordprocessor would be provided access to certain regions on a disk and thefiles associated therewith. The user could retrieve these files, deletethem, modify them and restore them. However, the user would not beallowed through the word processor to access the accounting database forany purpose, since operation of the word processor process does notrequire this. In another example, if a modem were provided, this wouldnot usually be a resource that was available to a word processor. Themodem, for example, could only be accessed by a communications program.

[0057] In an example of the operation of a process based securitysystem, reference is made to Table 2: TABLE 2 Process or applicationStep name Resource name Rights Mask 1 C:\*.*/S C:\*.*/S Full accessE:\LOGIN\LOGIN.EXE Execute only 2 E:\LOGIN\LOGIN.EXE E:\SYSTEM\PASSWORDSRead only E:\PROGRAMS\MENU\MENU.EXE Execute only 3E;\PROGRAMS\MENU\MEMU.EXE E:\PROGRAMS\MENU\SCREENS Read onlyE:\PROGRAMS\*.EXE/S Execute only E:\PROGRAMS\*.COM/S Execute only 4E:\PROGRAMS\WP51\WP.EXE F:\LIBRARY\*.* Full access G:\COMMON\*.*/S Fullaccess

[0058] For purposes of illustration, the example in Table 2 applies to apersonal computer (PC) which is attached to a network and running an MSDOS operating system that is provided with process-based security.Although a PC is usually considered a general purpose system, thesimplicity of the illustration provided by Table 1 applies equally wellto a dedicated computer system. When the computer is started, as in step1 in Table 1 described previously, any process to be run with the C:\drive (denoted with the wild card designation *.*) and itssub-directories (denoted with the /S option on the end of the processname) is provided full access to any resource on the C:\ drive. Notealso that the user can execute the resource E:\LOGIN\LOGIN.EXE from thenetwork but that all other resources from the network are not availableto the computer at this time as being limited by the statementE:\LOGIN\LOGIN.EXE. This statement will be described further in the nextparagraph. This example, so far, represents a user, on a computer, whocan log into a network, but has not done so. In essence, the user can doanything with his or her local resources, but nothing with networkresources, until they are identified to the network with the loginprogram.

[0059] In step 2 in Table 2, when the user executes theE:\LOGIN\LOGIN.EXE process, the process changes from something on C:\ toLOGIN.EXE which is permitted to read the E:\SYSTEM\PASSWORDS file andexecute the E:\PROGRAMS\MENU\MENU.EXE program. The file LOGIN.EXE is thenetwork's method of identifying users of the network. Execution ofLOGIN.EXE will verify the user through its read-only access to theE:\SYSTEM\PASSWORDS file. If the user is verified as a valid user,LOGIN.EXE will pass control on to step 3 and the processE:\PROGRAMS\MENU\MENU.EXE.

[0060] In step 3, when the file MENU\.EXE is executed, it will read theappropriate menu options from its SCREENS file and display it for theuser. MENU.EXE controls what programs can be executed and as such, ithas been given rights to execute any program in the E:\PROGRAMSdirectory or any of E:\PROGRAMS sub-directories (this is denoted withthe /S option after the partial wild card name *.EXE and *.COM as listedin the resources column of Table 2). In step 4, in the event the userexecutes the WP.EXE program, this process has full access to a localF:\LIBRARY directory, a shared G:\COMMON directory and thesub-directories of G:\COMMON. Step 4 may also represent a network, wherepersonal files are stored in a user-related directory (F:\LIBRARY) andcompany shared documents are stored in a common directory (G:\COMMON).

[0061] In the preceding examples illustrated by Table 2, it can be seenthat the user, because of the table which must be accessed during aresource request, cannot obtain access to the PASSWORDS file by anyother process except via the LOGIN.EXE process. This process alsodetermines how the user can deal with that particular file.

[0062] Referring now to FIG. 10 there is illustrated a flowchart of theoperation of the illustrative embodiment of the process-based securitysystem of FIG. 9. The flow begins with the Start block 200 and proceedsto block 204 to load the application program. From block 204 the flowproceeds to block 206 to start the application which is followed bydecision block 208 to determine whether a resource is requested by theapplication. If the result of the determination is negative then theflow follows the N path back to the entry to the Start Application block206. If the determination in block 208 is affirmative then the flowproceeds to block 218 wherein a step to read the respective resourceaccess table 164 for the requesting application 168 is performed.

[0063] Continuing further with FIG. 10, upon reading the resource accesstable 164 for the requested application in block 218 the flow proceedsto block 220 wherein the system 160 interprets the entries or statementsin the resource access table 166 to identify the commands of theexecution path and the sequence of operations contained in it. The flowthereupon proceeds to decision block 222 wherein a determination is madeas to whether the request for resource access matches the application inoperation. If the determination is negative, then the flow proceeds toblock 216 wherein access is denied and thereupon is routed back to thestart application block 206. If, however, the determination in decisionblock 222 is affirmative, then the flow proceeds along the Y path toblock 226 wherein access is granted to the requested resource and theflow returns to the main program to execute the application or processas indicated at block 234. It will be appreciated that the securityaccess is provided by the reading and interpreting of the resourceaccess table 164 entries or statements which specify the resourcesneeded for the particular application or process and the execution pathfor access to those resources. Thus, access to resources is limited toonly those resources that are needed and requested by the particularapplication or process that is in operation.

[0064] A study of FIGS. 9 and 10 described hereinabove will reveal thefollowing operational characteristics of a process-based security systemfor dedicated or single-purpose computer systems. Upon launching anapplication in a process-based system, the access rights are associatedor bound to the launched application as indicated by links 165, 166 and167 in FIG. 9. During the request for access to the needed resource(s),the access rights associated with that program are checked. In a generalpurpose system, security checks impede processing by interrupting the OSwhile the security check is performed each time a user requests aresource. In a dedicated system running one process or a single processcombination, only one request for resource access is required; ifseveral process combinations are provided, the system selectively allowsaccess to the resources appropriate to the process requesting access. Ineither case, the request occurs during the initial steps of the process.Further, the security access is performed by matching the conditionspresent upon launching the application such as the program identity,user identity and password, execution path through the directory, etc.with the resource access entries or statements in the respectiveresource access table 164. Once the application is launched, read andwrite calls are no longer checked, and the resource access table 164controls “the traffic”—the execution path through the directory. As anexample, in a web server application, the steps, briefly, would be: (1)turn on the web server; (2) launch the application, (3) read andinterpret the resource access table entries; (4) grant the neededaccess; and (5) execute the application, including the allowedresources.

[0065] During the interpretation step 220 of FIG. 10 of the illustratedembodiment, resource access table entries are interpreted, one characterat a time, instead of merely reading a resource name associated with alisted process or merely making a string comparison, because of thepresence of meta symbols embedded into the entries in the respectiveresource access table 164. Meta symbols, as disclosed herein, aretextual devices which may be inserted into resource access table entriesas second-order data or instructions to supply additional relatedinformation or modify the interpretation of the entry in some way. Inthe comparison process to find a resource in the resource access table,entries do not have to be static. Entries in the resource access tablecan have meta symbols to allow for context sensitivity to the processmaking the request. Table 3 presents some examples of meta symbolsdeveloped for the embodiment of the present disclosure which may beincluded in a resource access table entry. Meta symbols are assigned—andconstrued—in a UNIX environment. TABLE 3 Meta Symbol Definition/Meaning$P If the requested resource name matches to this point, consider theentry a match (path wild-card). $C The particular character in therequested resource name matches this symbol no matter what (characterwild-card). $D For a single level of depth in the directory, this symbolmeans a match (directory wild-card). $$ Requested resource name mustmatch a $ at this point. $S Requested resource name must end (suffix) inthe text following this symbol. $U Requested resource name must have theuser name of the user that initiated the process making the request, atthis point. $G Requested resource name must have the group name of thegroup that initiated the process making the request, at this group.

[0066] As described in the foregoing, to provide process-based securityaccess in a single-purpose “appliance” computer system, a resourceaccess table (RAT) is bound to, i.e., associated with, the requestingprocess when the process or application is launched. The RAT containsentries in which the defined execution paths, i.e., process paths, aremodified using meta symbols. These meta symbols provide instructions forinterpreting the process or execution paths. For example, meta symbolentries enable the system to determine which part(s) of an entry in aRAT must be matched character-by-character to produce a valid comparisonor which part(s) may be ignored or which part(s) has a substitutedinstruction, etc., in order to be granted the security access rightsassociated with that particular entry in the RAT. Each entry orstatement in the RAT may correspond to a resource whose access isdefined by the entry.

[0067] For example, an unmodified entry in a RAT might appear as:

[0068] PROGRAMS/WP/WP.EXE

[0069] and the resources to be associated therewith might be:

[0070] /HOME/$U/$P.

[0071] So, when a user initiates a program operation the command stringis compared to the RAT entry. In this example, the meta symbol $U meansthat the current user name is substituted into the entry and permittedaccess to the respective resource. Similarly, the $P modifies the RATentry and means that the rest of the path is ignored, i.e., it is“matched” no matter what the rest of the path is.

EXAMPLE NO. 1:

[0072] Referring now to FIG. 11, suppose the user Q is operating in thehome directory and wishes to delete a file xyz. In FIG. 11, theperspective is that of the operating system. The routine begins with thestart block 240 and proceeds to function block 242 wherein the operatingsystem (OS) receives a request to run DEL program. Thereafter the OSchecks in block 244 whether the current user is allowed a DEL command.If not, the flow follows the N path and returns to enter block 242. Ifso, the flow proceeds to block 246 to load the DEL command and fetch thecorresponding access rights from the resource access table (RAT) 166. Inthis case the RAT 166 entry is the statement: /HOME/$U/$P which definesaccess rights in the HOME directory for the $U current user within whichaccess is allowed $P from this point on, i.e., is unrestricted indirectory depth per Table 3.

[0073] Continuing with FIG. 11, in the next step, at decision block 248,the OS determines whether the access rights match the current user andif affirmative, the flow proceeds along the Y path to another decisionblock 250. There, if both the HOME directory and the current user $U arematched, the routine advances to block 252 where access is granted andthe DEL command is allowed to be executed. The routine returns to themain program in block 254. In either case, in blocks 248 or 250, theresult is that a match did not occur, access is denied and the routinereturns to the entry of block 242.

EXAMPLE #2:

[0074] Suppose the user is operating in the HOME directory, and wishesto run a word processor (e.g. WordPerfect). The word processor program(application or process) is in the directory: /PROGRAMS/WP/WP.EXE. Here,the resource access table statement is: /HOME/$U/$S.WP, where $S is usedas an intervening suffix. This statement limits access to files in theuser's home directory (/HOME/$U/) that end in the characters .WP($S.WP).

[0075] It will be appreciated in the foregoing example that any resourcecan be moved to any place in an execution path it is desired, merely bydefining the access rights for that path in the Resource Access Table.Thus, the access rights “move” with the new placement of the resource.Further, many resources, e.g., utility programs, can be wild carded intopart of an execution path. In effect, these programs are executed, notout of the original program or process but out of the resource accesstable 166. This provides a simple way to limit access rights—merely bystatements in the resource access table. Moreover, since the substituteddirectory path identified the word processor WP in its executionpath—and not some other resource such as an EXCEL program—access rightsto EXCEL (or any other program that may be part of the system) areexcluded from the WP program execution path.

[0076] Suppose, alternatively, the user is running EXCEL and wishes touse a spell check resource. Unless that spell check resource, whichresides in the WP program, is included in the allowed access rights ofthe RAT entries for the EXCEL program any user attempt to access it fromEXCEL will be denied. It will thus be appreciated that the process-basedsecurity described hereinabove provides the advantages of (1) preventingusers from loading their own applications on a dedicated systemconfigured according to the present disclosure; and (2) preventing usersfrom attempting to access files via uncontrolled ways such as trying toload in a hex editor, e.g., to obtain access to accounting or othersensitive files.

[0077] EXAMPLE NO. 3 :

[0078] Consider a web server (WS) which can execute any common gatewayinterface (CGI) serving a plurality of companies, e.g., A, B, C, D, Eand F. Prefixing is used to distinguish whose CGI is allowed execution(e.g., ABC/CGI for access to ABC/DATA directory but which may excludeDEF/CGI) by substitution according to a $E(#) meta symbol thatidentifies the path that is executable out of the original structure inthe RAT. In the RAT, as illustrated in Table 4 hereinbelow, it is seenthat there are two kinds of entries instead of one: one statement forthe web server, another for the CGI for which access rights are defined.Table 4 illustrates a fragment of the RAT for Example 3. TABLE 4 WebServer CGI Rights /HTTP /PROGRAMS/$D/$P Execution /PROGRAMS/$D/$P$E(2)/DATA/$P Read, Write

[0079] Here, the path /PROGRAMS/ABC is granted access, according to thestatement $E(2)/DATA/$P.

[0080] The resource access table 166 entries, thus modified by metasymbols, as described hereinabove, define both the access to resourcesand the execution path through the directory. The resource access table166, uniquely determined for the dedicated, single purpose system, iscalled by the request for access made by the application or process.Thus, the entries in the resource access table are, at the same time,both statements of the access rights and statements of the executionpath. In some operations, for example, a meta symbol (identified by a $followed by a character) inserted into a statement in the resourceaccess table may provide for, referring to Table 3:

[0081] (1) association of user identity information with the applicationor process (user ID and a password, e.g.);

[0082] (2) substitution of one user or a group of users for anotheruser;

[0083] (3) substitution of a part of one execution path for another one;

[0084] (4) specifying at what point in the directory path the accessbegins, or how far into the directory the access rights extend; and

[0085] (5) specifying an access path limited to a particular file nameor keyed to the access of a particular file. The meta symbols enablemodifications to the entries in the resource access table 166 withinstructions that define, on the fly, the particular access rightsavailable to a particular process. Thus, instead of just performing astring comparison of the access rights string (with a predetermined setof access rights) the string is read and interpreted, based on itscontent, as it proceeds on the execution path.

[0086] In summary, the process-based security as disclosed hereinaboveis most efficiently applied to specific functions. The operating system162 of the dedicated, single-purpose system 160 is bundled only with thespecific applications 168 needed including the resource access tables166 and the necessary code to implement the use of the meta symbols andthe process-based security access. Only internal resources are affected.Requests for access to resources 172 are processed from within theparticular process or application 168 before invoking the operatingsystem 162 but before the request handler is invoked.

[0087] Although the illustrative embodiment has been described indetail, it should be understood that various changes, substitutions andalterations can be made therein without departing from the spirit andscope of the invention as defined by the appended claims.

What is claimed is:
 1. A method for providing process-based security ina special purpose computer system, comprising the steps of: configuringthe special purpose computer with an operating system and at least oneapplication for operation as a computer appliance; associating aresource access table with each at least one application, addressable bythe at least one application, the resource access table containingstatements corresponding to predetermined requests for access to atleast a one specified resource during running of the at least oneapplication wherein the resource access table statements includeinformation defining an execution path for the at least one application;interpreting the resource access table statements upon a request for thespecified resource by the at least one application, wherein a successfulmatch of the statements in the resource access table with conditionspresent upon launching the at least one application determines securityaccess prior to granting access to the specified resource; and causingthe execution of the at least one application, upon granting access tothe requested resource, including the use of the requested resourceaccording to the execution path statements in the resource access table.2. The method of claim 1, wherein the step of installing a resourceaccess table comprises the steps of: configuring the resource accesstable addressable by the at least one application to associate with theat least one application a list of at least one specified resource in apredetermined sequence according to need for the at least one specifiedresource and corresponding with an index indicating when the at leastone specified resource is to be requested; and constructing the resourceaccess table statements to define each execution path associated with aspecified resource for the at least one application.
 3. The method ofclaim 1, wherein the step of interpreting the resource access tablestatements comprises the steps of: detecting when present a meta symbolembedded in a resource access table statement to modify the executionpath associated with the specified resource; and executing thecorresponding instruction conveyed by the meta symbol to control theaccess to the specified resource.
 4. The method of claim 3, wherein thestep of executing the corresponding instruction comprises the steps of:verifying that the access rights obtained match the access rights neededby the application; and responding to the request for access to the atleast one application program.
 5. The method of claim 4, wherein thestep of verifying comprises the step of: granting access to thespecified resource if a successful match is verified.
 6. The method ofclaim 4, wherein the step of verifying comprises the step of: denyingaccess to the specified resource if a successful match is not verified.7. The method of claim 1, wherein the step of causing the execution ofthe at least one application comprises the steps of: starting theoperating system; identifying the at least one application; associatingthe corresponding resource access table to the identified application;running the at least one application; and executing the execution pathaccording to the statements in the resource access table.
 8. A methodfor securing resource access in a special purpose computer system,comprising the steps of: configuring the special purpose computer systemwith an operating system and at least one application for operation as acomputer appliance; launching an application on the special purposecomputer system; processing a resource request called by the at leastone application program; determining whether resource access is to begranted based on a resource access table associated with the at leastone application.
 9. The method of claim 8, wherein the step of launchingfurther comprises the step of associating the resource access table tothe at least one application.
 10. The method of claim 8, wherein thestep of processing further comprises the steps of: accessing a resourceaccess table associated with the requesting application; and reading theresource access table to establish resources that may be made availableto the requested application.
 11. The method of claim 10, wherein thestep of accessing further comprises the step of setting up the executionpath according to the resource access table.
 12. The method of claim 11,wherein the step of setting up the execution path further comprises thestep of granting access to the requested resource.
 13. The method ofclaim 10, wherein the step of accessing further comprises the step ofinterpreting execution path entries in the resource access table. 14.The method of claim 10, wherein the step of reading comprises the stepof: interpreting execution path entries in the resource access table;and matching the execution path entries with the name of the at leastone application.
 15. The method of claim 11, wherein the step ofmatching comprises the steps of: denying access if a match does notoccur; and granting access if a match does occur.
 16. The method ofclaim 8, wherein the step of running the at least one applicationfurther comprises the step of executing the specified execution path.17. Apparatus for providing process-based security in a special purposecomputer system, comprising: a special purpose computer configured withan operating system and at least one application program for operationas a computer appliance wherein said special purpose computer has accessto a plurality of resources for use by said at least one application; aresource access table associated with said at least one applicationprogram and containing execution path statements corresponding topredetermined requests for access to at least a one specified resourceduring running of said at least one application wherein said resourceaccess table statements include information defining an execution pathfor said at least one application; access control means within saidoperating system and responsive to said resource access table forinterpreting said resource access table statements upon a request for aspecified resource by said at least one application wherein a successfulmatch of said statements in said resource access table with conditionspresent upon launching the at least one application determines securityaccess prior to granting access to said specified resource; andexecution means for executing said at least one application program,upon granting access to said specified resource, according to saidstatements in said resource access table.
 18. The apparatus of claim 17,wherein said resource access table comprises: in association with eachsaid at least one application a list of said plurality of resourcesarranged in a predetermined sequence according to need for each one ofsaid plurality of resources, said list corresponding with an indexindicating when each said one of said plurality of resources is to berequested.
 19. The apparatus of claim 17, wherein said resource accesstable comprises: one or more instruction statements associated with eachsaid application program entry for controlling access to said resourcein accordance with said execution path.
 20. The apparatus of claim 19,wherein said one or more instruction statements contains at least oneembedded meta symbol for modifying said execution path.
 21. Theapparatus of claim 17, wherein said access control means comprises: aprogram for detecting meta symbols embedded in said statements of saidresource access table and interpreting said statements responsive tosaid request for access by said at least one application, therebyproviding execution path instructions.